/*
 *==========================================================================
 *
 *      xyzModem.c
 *
 *      RedBoot stream handler for xyzModem protocol
 *
 *==========================================================================
 * SPDX-License-Identifier:    eCos-2.0
 *==========================================================================
 *#####DESCRIPTIONBEGIN####
 *
 * Author(s):    gthomas
 * Contributors: gthomas, tsmith, Yoshinori Sato
 * Date:         2000-07-14
 * Purpose:
 * Description:
 *
 * This code is part of RedBoot (tm).
 *
 *####DESCRIPTIONEND####
 *
 *==========================================================================
 */
#include "xyzModem.h"

/* Assumption - run xyzModem protocol over the console port */

/* Values magic to the protocol */
#define SOH 0x01
#define STX 0x02
#define EOT 0x04
#define ACK 0x06
#define BSP 0x08
#define NAK 0x15
#define CAN 0x18
#define EOF 0x1A        /* ^Z for DOS officionados */

/* Data & state local to the protocol */
static struct
{
  int *__chan;
  unsigned char pkt[1024], *bufp;
  unsigned char blk, cblk, crc1, crc2;
  unsigned char next_blk;    /* Expected block */
  int len, mode, total_retries;
  int total_SOH, total_STX, total_CAN;
  bool crc_mode, at_eof, tx_ack;
  unsigned long file_length, read_length;
} xyz;

#define xyzModem_CHAR_TIMEOUT            2000    /* 2 seconds */
#define xyzModem_MAX_RETRIES             20
#define xyzModem_MAX_RETRIES_WITH_CRC    10
#define xyzModem_CAN_COUNT                3    /* Wait for 3 CAN before quitting */


typedef int cyg_int32;
static int
CYGACC_COMM_IF_GETC_TIMEOUT (char chan, char *c)
{

  ulong now = get_timer(0);
  while (!tstc ())
    {
      if (get_timer(now) > xyzModem_CHAR_TIMEOUT)
        break;
    }
  if (tstc ())
    {
      *c = getc ();
      return 1;
    }
  return 0;
}

static void
CYGACC_COMM_IF_PUTC (char x, char y)
{
  putc (y);
}

/* Validate a hex character */
__inline__ static bool
_is_hex (char c)
{
  return (((c >= '0') && (c <= '9')) ||
      ((c >= 'A') && (c <= 'F')) || ((c >= 'a') && (c <= 'f')));
}

/* Convert a single hex nibble */
__inline__ static int
_from_hex (char c)
{
  int ret = 0;

  if ((c >= '0') && (c <= '9'))
    {
      ret = (c - '0');
    }
  else if ((c >= 'a') && (c <= 'f'))
    {
      ret = (c - 'a' + 0x0a);
    }
  else if ((c >= 'A') && (c <= 'F'))
    {
      ret = (c - 'A' + 0x0A);
    }
  return ret;
}

/* Convert a character to lower case */
__inline__ static char
_tolower (char c)
{
  if ((c >= 'A') && (c <= 'Z'))
    {
      c = (c - 'A') + 'a';
    }
  return c;
}

/* Parse (scan) a number */
static bool
parse_num (char *s, unsigned long *val, char **es, char *delim)
{
  bool first = true;
  int radix = 10;
  char c;
  unsigned long result = 0;
  int digit;

  while (*s == ' ')
    s++;
  while (*s)
    {
      if (first && (s[0] == '0') && (_tolower (s[1]) == 'x'))
    {
      radix = 16;
      s += 2;
    }
      first = false;
      c = *s++;
      if (_is_hex (c) && ((digit = _from_hex (c)) < radix))
    {
      /* Valid digit */
      result = (result * radix) + digit;
    }
      else
    {
      if (delim != (char *) 0)
        {
          /* See if this character is one of the delimiters */
          char *dp = delim;
          while (*dp && (c != *dp))
        dp++;
          if (*dp)
        break;        /* Found a good delimiter */
        }
      return false;        /* Malformatted number */
    }
    }
  *val = result;
  if (es != (char **) 0)
    {
      *es = s;
    }
  return true;
}


#ifdef USE_DBG_BUF
/*
 * Note: this debug setup works by storing the strings in a fixed buffer
 */
static char zm_debug_buf[8192];
static char *zm_out = zm_debug_buf;
static char *zm_out_start = zm_debug_buf;

static int
zm_dprintf (char *fmt, ...)
{
  int len;
  va_list args;

  va_start (args, fmt);
  len = diag_vsprintf (zm_out, fmt, args);
  zm_out += len;
  return len;
}

static void
zm_flush (void)
{
  zm_out = zm_out_start;
}

static void
zm_dump_buf (void *buf, int len)
{

}

static unsigned char zm_buf[2048];
static unsigned char *zm_bp;

static void
zm_new (void)
{
  zm_bp = zm_buf;
}

static void
zm_save (unsigned char c)
{
  *zm_bp++ = c;
}

static void
zm_dump (int line)
{
  zm_dprintf ("Packet at line: %d\n", line);
  zm_dump_buf (zm_buf, zm_bp - zm_buf);
}

#define ZM_DEBUG(x) x
#else
#define ZM_DEBUG(x)
#endif

/* Wait for the line to go idle */
static void
xyzModem_flush (void)
{
  int res;
  char c;
  while (true)
    {
      res = CYGACC_COMM_IF_GETC_TIMEOUT (*xyz.__chan, &c);
      if (!res)
    return;
    }
}

static int
xyzModem_get_hdr (void)
{
  char c;
  int res;
  bool hdr_found = false;
  int i, can_total, hdr_chars;
  unsigned short cksum;

  ZM_DEBUG (zm_new ());
  /* Find the start of a header */
  can_total = 0;
  hdr_chars = 0;

  if (xyz.tx_ack)
    {
      CYGACC_COMM_IF_PUTC (*xyz.__chan, ACK);
      xyz.tx_ack = false;
    }
  while (!hdr_found)
    {
      res = CYGACC_COMM_IF_GETC_TIMEOUT (*xyz.__chan, &c);
      ZM_DEBUG (zm_save (c));
      if (res)
    {
      hdr_chars++;
      switch (c)
        {
        case SOH:
          xyz.total_SOH++;
        case STX:
          if (c == STX)
        xyz.total_STX++;
          hdr_found = true;
          break;
        case CAN:
          xyz.total_CAN++;
          ZM_DEBUG (zm_dump (__LINE__));
          if (++can_total == xyzModem_CAN_COUNT)
        {
          return xyzModem_cancel;
        }
          else
        {
          /* Wait for multiple CAN to avoid early quits */
          break;
        }
        case EOT:
          /* EOT only supported if no noise */
          if (hdr_chars == 1)
        {
          CYGACC_COMM_IF_PUTC (*xyz.__chan, ACK);
          ZM_DEBUG (zm_dprintf ("ACK on EOT #%d\n", __LINE__));
          ZM_DEBUG (zm_dump (__LINE__));
          return xyzModem_eof;
        }
        default:
          /* Ignore, waiting for start of header */
          ;
        }
    }
      else
    {
      /* Data stream timed out */
      xyzModem_flush ();    /* Toss any current input */
      ZM_DEBUG (zm_dump (__LINE__));
      CYGACC_CALL_IF_DELAY_US ((cyg_int32) 250000);
      return xyzModem_timeout;
    }
    }

  /* Header found, now read the data */
  res = CYGACC_COMM_IF_GETC_TIMEOUT (*xyz.__chan, (char *) &xyz.blk);
  ZM_DEBUG (zm_save (xyz.blk));
  if (!res)
    {
      ZM_DEBUG (zm_dump (__LINE__));
      return xyzModem_timeout;
    }
  res = CYGACC_COMM_IF_GETC_TIMEOUT (*xyz.__chan, (char *) &xyz.cblk);
  ZM_DEBUG (zm_save (xyz.cblk));
  if (!res)
    {
      ZM_DEBUG (zm_dump (__LINE__));
      return xyzModem_timeout;
    }
  xyz.len = (c == SOH) ? 128 : 1024;
  xyz.bufp = xyz.pkt;
  for (i = 0; i < xyz.len; i++)
    {
      res = CYGACC_COMM_IF_GETC_TIMEOUT (*xyz.__chan, &c);
      ZM_DEBUG (zm_save (c));
      if (res)
    {
      xyz.pkt[i] = c;
    }
      else
    {
      ZM_DEBUG (zm_dump (__LINE__));
      return xyzModem_timeout;
    }
    }
  res = CYGACC_COMM_IF_GETC_TIMEOUT (*xyz.__chan, (char *) &xyz.crc1);
  ZM_DEBUG (zm_save (xyz.crc1));
  if (!res)
    {
      ZM_DEBUG (zm_dump (__LINE__));
      return xyzModem_timeout;
    }
  if (xyz.crc_mode)
    {
      res = CYGACC_COMM_IF_GETC_TIMEOUT (*xyz.__chan, (char *) &xyz.crc2);
      ZM_DEBUG (zm_save (xyz.crc2));
      if (!res)
    {
      ZM_DEBUG (zm_dump (__LINE__));
      return xyzModem_timeout;
    }
    }
  ZM_DEBUG (zm_dump (__LINE__));
  /* Validate the message */
  if ((xyz.blk ^ xyz.cblk) != (unsigned char) 0xFF)
    {
      ZM_DEBUG (zm_dprintf
        ("Framing error - blk: %x/%x/%x\n", xyz.blk, xyz.cblk,
         (xyz.blk ^ xyz.cblk)));
      ZM_DEBUG (zm_dump_buf (xyz.pkt, xyz.len));
      xyzModem_flush ();
      return xyzModem_frame;
    }
  /* Verify checksum/CRC */
  if (xyz.crc_mode)
    {
      cksum = crc16_ccitt(0, xyz.pkt, xyz.len);
      if (cksum != ((xyz.crc1 << 8) | xyz.crc2))
    {
      ZM_DEBUG (zm_dprintf ("CRC error - recvd: %02x%02x, computed: %x\n",
                xyz.crc1, xyz.crc2, cksum & 0xFFFF));
      return xyzModem_cksum;
    }
    }
  else
    {
      cksum = 0;
      for (i = 0; i < xyz.len; i++)
    {
      cksum += xyz.pkt[i];
    }
      if (xyz.crc1 != (cksum & 0xFF))
    {
      ZM_DEBUG (zm_dprintf
            ("Checksum error - recvd: %x, computed: %x\n", xyz.crc1,
             cksum & 0xFF));
      return xyzModem_cksum;
    }
    }
  /* If we get here, the message passes [structural] muster */
  return 0;
}

int
xyzModem_stream_open (connection_info_t * info, int *err)
{
  int stat = 0;
  int retries = xyzModem_MAX_RETRIES;
  int crc_retries = xyzModem_MAX_RETRIES_WITH_CRC;

/*    ZM_DEBUG(zm_out = zm_out_start); */
#ifdef xyzModem_zmodem
  if (info->mode == xyzModem_zmodem)
    {
      *err = xyzModem_noZmodem;
      return -1;
    }
#endif

/* TODO: CHECK ! */
  int dummy = 0;
  xyz.__chan = &dummy;
  xyz.len = 0;
  xyz.crc_mode = true;
  xyz.at_eof = false;
  xyz.tx_ack = false;
  xyz.mode = info->mode;
  xyz.total_retries = 0;
  xyz.total_SOH = 0;
  xyz.total_STX = 0;
  xyz.total_CAN = 0;
  xyz.read_length = 0;
  xyz.file_length = 0;

  CYGACC_COMM_IF_PUTC (*xyz.__chan, (xyz.crc_mode ? 'C' : NAK));

  if (xyz.mode == xyzModem_xmodem)
    {
      /* X-modem doesn't have an information header - exit here */
      xyz.next_blk = 1;
      return 0;
    }

  while (retries-- > 0)
    {
      stat = xyzModem_get_hdr ();
      if (stat == 0)
    {
      /* Y-modem file information header */
      if (xyz.blk == 0)
        {
          /* skip filename */
          while (*xyz.bufp++);
          /* get the length */
          parse_num ((char *) xyz.bufp, &xyz.file_length, NULL, " ");
          /* The rest of the file name data block quietly discarded */
          xyz.tx_ack = true;
        }
      xyz.next_blk = 1;
      xyz.len = 0;
      return 0;
    }
      else if (stat == xyzModem_timeout)
    {
      if (--crc_retries <= 0)
        xyz.crc_mode = false;
      CYGACC_CALL_IF_DELAY_US (5 * 100000);    /* Extra delay for startup */
      CYGACC_COMM_IF_PUTC (*xyz.__chan, (xyz.crc_mode ? 'C' : NAK));
      xyz.total_retries++;
      ZM_DEBUG (zm_dprintf ("NAK (%d)\n", __LINE__));
    }
      if (stat == xyzModem_cancel)
    {
      break;
    }
    }
  *err = stat;
  ZM_DEBUG (zm_flush ());
  return -1;
}

int
xyzModem_stream_read (char *buf, int size, int *err)
{
  int stat, total, len;
  int retries;

  total = 0;
  stat = xyzModem_cancel;
  /* Try and get 'size' bytes into the buffer */
  while (!xyz.at_eof && (size > 0))
    {
      if (xyz.len == 0)
    {
      retries = xyzModem_MAX_RETRIES;
      while (retries-- > 0)
        {
          stat = xyzModem_get_hdr ();
          if (stat == 0)
        {
          if (xyz.blk == xyz.next_blk)
            {
              xyz.tx_ack = true;
              ZM_DEBUG (zm_dprintf
                ("ACK block %d (%d)\n", xyz.blk, __LINE__));
              xyz.next_blk = (xyz.next_blk + 1) & 0xFF;

              if (xyz.mode == xyzModem_xmodem || xyz.file_length == 0)
            {
              /* Data blocks can be padded with ^Z (EOF) characters */
              /* This code tries to detect and remove them */
              if ((xyz.bufp[xyz.len - 1] == EOF) &&
                  (xyz.bufp[xyz.len - 2] == EOF) &&
                  (xyz.bufp[xyz.len - 3] == EOF))
                {
                  while (xyz.len
                     && (xyz.bufp[xyz.len - 1] == EOF))
                {
                  xyz.len--;
                }
                }
            }

              /*
               * See if accumulated length exceeds that of the file.
               * If so, reduce size (i.e., cut out pad bytes)
               * Only do this for Y-modem (and Z-modem should it ever
               * be supported since it can fall back to Y-modem mode).
               */
              if (xyz.mode != xyzModem_xmodem && 0 != xyz.file_length)
            {
              xyz.read_length += xyz.len;
              if (xyz.read_length > xyz.file_length)
                {
                  xyz.len -= (xyz.read_length - xyz.file_length);
                }
            }
              break;
            }
          else if (xyz.blk == ((xyz.next_blk - 1) & 0xFF))
            {
              /* Just re-ACK this so sender will get on with it */
              CYGACC_COMM_IF_PUTC (*xyz.__chan, ACK);
              continue;    /* Need new header */
            }
          else
            {
              stat = xyzModem_sequence;
            }
        }
          if (stat == xyzModem_cancel)
        {
          break;
        }
          if (stat == xyzModem_eof)
        {
          CYGACC_COMM_IF_PUTC (*xyz.__chan, ACK);
          ZM_DEBUG (zm_dprintf ("ACK (%d)\n", __LINE__));
          if (xyz.mode == xyzModem_ymodem)
            {
              CYGACC_COMM_IF_PUTC (*xyz.__chan,
                       (xyz.crc_mode ? 'C' : NAK));
              xyz.total_retries++;
              ZM_DEBUG (zm_dprintf ("Reading Final Header\n"));
              stat = xyzModem_get_hdr ();
              CYGACC_COMM_IF_PUTC (*xyz.__chan, ACK);
              ZM_DEBUG (zm_dprintf ("FINAL ACK (%d)\n", __LINE__));
            }
          xyz.at_eof = true;
          break;
        }
          CYGACC_COMM_IF_PUTC (*xyz.__chan, (xyz.crc_mode ? 'C' : NAK));
          xyz.total_retries++;
          ZM_DEBUG (zm_dprintf ("NAK (%d)\n", __LINE__));
        }
      if (stat < 0)
        {
          *err = stat;
          xyz.len = -1;
          return total;
        }
    }
      /* Don't "read" data from the EOF protocol package */
      if (!xyz.at_eof)
    {
      len = xyz.len;
      if (size < len)
        len = size;
      memcpy (buf, xyz.bufp, len);
      size -= len;
      buf += len;
      total += len;
      xyz.len -= len;
      xyz.bufp += len;
    }
    }
  return total;
}

void
xyzModem_stream_close (int *err)
{
  diag_printf
    ("xyzModem - %s mode, %d(SOH)/%d(STX)/%d(CAN) packets, %d retries\n",
     xyz.crc_mode ? "CRC" : "Cksum", xyz.total_SOH, xyz.total_STX,
     xyz.total_CAN, xyz.total_retries);
  ZM_DEBUG (zm_flush ());
}

/* Need to be able to clean out the input buffer, so have to take the */
/* getc */
void
xyzModem_stream_terminate (bool abort, int (*getc) (void))
{
  int c;

  if (abort)
    {
      ZM_DEBUG (zm_dprintf ("!!!! TRANSFER ABORT !!!!\n"));
      switch (xyz.mode)
    {
    case xyzModem_xmodem:
    case xyzModem_ymodem:
      /* The X/YMODEM Spec seems to suggest that multiple CAN followed by an equal */
      /* number of Backspaces is a friendly way to get the other end to abort. */
      CYGACC_COMM_IF_PUTC (*xyz.__chan, CAN);
      CYGACC_COMM_IF_PUTC (*xyz.__chan, CAN);
      CYGACC_COMM_IF_PUTC (*xyz.__chan, CAN);
      CYGACC_COMM_IF_PUTC (*xyz.__chan, CAN);
      CYGACC_COMM_IF_PUTC (*xyz.__chan, BSP);
      CYGACC_COMM_IF_PUTC (*xyz.__chan, BSP);
      CYGACC_COMM_IF_PUTC (*xyz.__chan, BSP);
      CYGACC_COMM_IF_PUTC (*xyz.__chan, BSP);
      /* Now consume the rest of what's waiting on the line. */
      ZM_DEBUG (zm_dprintf ("Flushing serial line.\n"));
      xyzModem_flush ();
      xyz.at_eof = true;
      break;
#ifdef xyzModem_zmodem
    case xyzModem_zmodem:
      /* Might support it some day I suppose. */
#endif
      break;
    }
    }
  else
    {
      ZM_DEBUG (zm_dprintf ("Engaging cleanup mode...\n"));
      /*
       * Consume any trailing crap left in the inbuffer from
       * previous received blocks. Since very few files are an exact multiple
       * of the transfer block size, there will almost always be some gunk here.
       * If we don't eat it now, RedBoot will think the user typed it.
       */
      ZM_DEBUG (zm_dprintf ("Trailing gunk:\n"));
      while ((c = (*getc) ()) > -1)
        ;
      ZM_DEBUG (zm_dprintf ("\n"));
      /*
       * Make a small delay to give terminal programs like minicom
       * time to get control again after their file transfer program
       * exits.
       */
      CYGACC_CALL_IF_DELAY_US ((cyg_int32) 250000);
    }
}

char *
xyzModem_error (int err)
{
  switch (err)
    {
    case xyzModem_access:
      return "Can't access file";
      break;
    case xyzModem_noZmodem:
      return "Sorry, zModem not available yet";
      break;
    case xyzModem_timeout:
      return "Timed out";
      break;
    case xyzModem_eof:
      return "End of file";
      break;
    case xyzModem_cancel:
      return "Cancelled";
      break;
    case xyzModem_frame:
      return "Invalid framing";
      break;
    case xyzModem_cksum:
      return "CRC/checksum error";
      break;
    case xyzModem_sequence:
      return "Block sequence error";
      break;
    default:
      return "Unknown error";
      break;
    }
}

/*
 * RedBoot interface
 */
